WASHINGTON Two Republican senators are drafting legislation that would unilaterally redefine U.S. commitments under the Iran nuclear deal , an agreement negotiated in 2015 between Iran, the U.S. and five other countries.

Under the terms of the nuclear accord, the U.S. and other countries have been providing sweeping sanctions relief to Iran in exchange for Iran significantly downsizing its nuclear program and giving international inspectors broad access to its nuclear sites. Some of the restrictions on Irans nuclear program expire or sunset after 10 to 15 years.

Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) and Sen. Tom Cotton (R-Ark.) are working to modify an existing law so that the U.S. will no longer honor those sunset clauses.

Under the envisioned legislation, the U.S.would automatically reimpose sanctions if Irans nuclear program approaches a point in which it could acquire a nuclear weapon in less than a year. The law would also call for the reimposition of sanctions if Iran took certain, still-unspecified steps related to its ballistic missile program, Corker told reporters on Friday.

A fact sheet that outlined the envisioned legislation did not specify which sanctions would be reimposed. But the broad outlines of the legislation indicate that the U.S. would sanction Iran for increasing the number of centrifuges it has spinning and the amount of low-enriched uranium it produces actions that Iran would otherwise be allowed to undertake in 10 to 15 years under the current agreement.

The proposed legislation was closely coordinated with the White House. This afternoon, President Donald Trump is expected to decertify the Iran deal and ask lawmakers to amend existing laws so that U.S. sanctions lifted under the nuclear deal will automatically be reimposed if Iran takes certain steps related to its nuclear and ballistic missile program.

Because of an oversight law passed by Congress in 2015, the president has to certify (or decertify) to Congress every 90 days whether Iran is complying with the nuclear accord and whether remaining party to the deal is in the U.S. national interest. Corker told reporters Friday he is aiming to pass legislation before the next certification deadline in three months. He hopes to introduce the text of the bill within the next two weeks, he said.

The proposed legislation would unilaterally change the terms of the nuclear deal, Colin Kahl, a former deputy assistant to President Barack Obama , tweeted on Friday.

Iran and possibly U.S. European allies who helped negotiate the deal would likely see this legislation as a U.S. violation of the international nuclear agreement.

Because the U.S. still has a primary embargo against Iran, it would likely reimpose secondary sanctions that penalize other countries for doing business with the country.

Corker, who opposed implementing the nuclear accord in 2015, has since expressed hesitation about killing the deal outright. But Cotton, one of the most hawkish members of Congress, has been open about his desire to scrap the agreement and has even advocated regime change in Tehran.

The Senate will consider the Corker-Cotton legislation using regular order, Corker said Friday, meaning the proposed bill would need 60 votes to clear the Senate. So far, no Democrat has endorsed the plan.

During a phone call with reporters, Corker argued that his proposed bill in no way violates the JCPOA, the acronym for the Iran deal.

But he stumbled in defending that position, at one point admitting that the bill would change the terms of the nuclear accord.

The proposed legislation would actually make it the kind of deal it should have been in the first place, Corker said Friday.

Corkers efforts to work with the White House to execute its Iran policy comes after a public feud between the president and the senator.

Trump mocked Corker earlier this week and alleged that the senator was not running for re-election because Trump had declined to endorse him. Corker, who denied that account, lamented that the White House has become an adult day care center and expressed concern that Trump would lead the country into World War III .

On Friday, Corker emphasized that even though he had coordinated extensively with the White House on its Iran strategy, Trump could always change his mind. When describing the current policy to reporters, Corker qualified his statements with as of 11:51 and as of 11:53.

Believe me guys, this is very fluid.